It's not single snapshots of empty shelves that prove this as you point out. What is needed is multiple data points showing shelf placement in stores and relative to other shelves.

A few stores I've used over the years have removed entire shelves from their floor because they no longer carry enough stock to keep the previous floor plan stocked. The easiest places to notice this are aisles where previously you may have issues passing another customer with a trolley you risked colliding with due to how narrow the aisle originally was.

Now? No risk of collision at all but nobody picks up on it or realises what that means.